The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhua...The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate(avg.5.50μW/m³)and a low Th/U ratio(avg.2.62).Uranium-rich granite and its alteration zone within the upper crust(0-5 km depth)contribute about 45%of the total radioactive heat production,wich is crucial for controlling geothermal resource distribution.For uranium-thermal at tectonic plate margins,a symbiotic geological model was proposed:Firstly,subduction of the Pacific Plate caused upwelling of the asthenosphere,generating a high heat-flow background.Secondly,heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults.Subsequently,uranium was mobilized,transported,and enriched within the granite through deep siliceous hydrothermal activity and associated alteration.Ultimately,the uranium enrichment in granite leads to increased radioactive heat production,resulting in local thermal anomalies.This model provides a theoretical support for exploring and developing uranium-thermal symbiotic resources in South China.展开更多
To clarify the effects of mechanical sowing and transplanting on dry mat- ter production of middle-season hybrid rice, a two-factor split plot design was used to study the effects of different sowing and transplanting...To clarify the effects of mechanical sowing and transplanting on dry mat- ter production of middle-season hybrid rice, a two-factor split plot design was used to study the effects of different sowing and transplanting methods and their interac- tion with the seedling number per hill or seeding time on dry matter accumulation, distribution and transformation of F You 498, a middle-season hybrid rice variety, under field conditions in 2012 and 2013. The results showed that there was a marked effect of the sowing and transplanting methods and their interaction with the seedling number per hill or seeding time on dry matter accumulation, distribution and transformation. The total population dry matter accumulation of the treatments with mechanical direct seeding （MDS） and machine-based transplanting （MT） was lower than that of the treatment with traditional manual transplanting （TMT）. How- ever, MDS had higher dry matter accumulation and accumulating rate in the joint- ing-earing stage,and maintained higher stem-sheath exportation, export rate and transformation than MT and TMT; MT had higher dry matter accumulation and ac- cumulating rate in the heading-maturity period than MDS and TMT. Moreover, the treatments with low seedling number per hill or early seeding enhanced the assimi- lation of dry matter after heading,the ratio of dry matter accumulation after earing to biomass yield and the contribution rate of dry matter accumulation after earing, and a reasonable early sowing was favorable to increase the harvest index of middle- season hybrid rice under mechanical sowing and transplanting conditions.展开更多
Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process...Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process of pressing, sintering, drawing, or rolling, respectively. By comparative analysis on the microstructure and mechanical properties of Mo wires and Mo sheets, the effect of Mo powder micro-morphology on properties and quality of Mo products was studied. The results show that, compared with that prepared by traditional Mo powder with inhomogeneous particle size and aggregation, the Mo wires prepared by specific Mo powder with homogeneous particle sizes, less agglomeration, and better dispersion exhibit higher yield, higher tensile strength, and lower elongation at room temperature, and the Mo sheets also show excellent high-temperature performances and better isotropy. The essential reason for those is the difference of Mo powder micro-morphology. Inhomogeneous particle size and aggregation of Mo powder greatly influence the microstructure of Mo sintered compacts and mechanical properties of Mo products.展开更多
An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements o...An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the elements.It divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve chains.The parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid elements.The average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve chains.Through the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between them.The method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning system.The examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering drawings.The dimension information is complete,accurate and reliable.展开更多
Based on questionnaire surveys and field interviews conducted with various types of agricultural production organizations across five districts and four counties in Daqing City,this study combines relevant theoretical...Based on questionnaire surveys and field interviews conducted with various types of agricultural production organizations across five districts and four counties in Daqing City,this study combines relevant theoretical frameworks to systematically examine the evolution,performance,and influencing factors of governance mechanisms within these organizations.Using both quantitative and inductive analytical methods,the paper proposes innovative designs and supporting measures for improving governance mechanisms.The findings reveal that,amid large-scale farmland circulation,the governance mechanisms of agricultural production organizations in Daqing City are evolving from traditional to modern structures.However,challenges remain in areas such as decision-making efficiency,benefit distribution,and supervision mechanisms.In response,this study proposes innovative governance designs focusing on decision-making processes,profit-sharing mechanisms,and risk prevention.Corresponding policy recommendations are also provided to support the sustainable development of agricultural modernization in China.展开更多
Myocardial infarction is a cardiovascular disease(CVD)with high morbidity and mortality,which can trigger a cascade of cardiac pathophysiological changes,including fibrosis,inflammation,ischemia-reperfusion injury(IRI...Myocardial infarction is a cardiovascular disease(CVD)with high morbidity and mortality,which can trigger a cascade of cardiac pathophysiological changes,including fibrosis,inflammation,ischemia-reperfusion injury(IRI),and ventricular remodeling,ultimately leading to heart failure(HF).While conventional pharmacological treatments and clinical reperfusion therapy may enhance short-term prognoses and emergency survival rates,both approaches have limitations and adverse effects.Natural products(NPs)are extensively utilized as therapeutics globally,with some demonstrating potentially favorable therapeutic effects in preclinical and clinical pharmacological studies,positioning them as potential alternatives to modern drugs.This review comprehensively elucidates the pathophysiological mechanisms during myocardial infarction and summarizes the mechanisms by which NPs exert cardiac beneficial effects.These include classical mechanisms such as inhibition of inflammation and oxidative stress,alleviation of cardiomyocyte death,attenuation of cardiac fibrosis,improvement of angiogenesis,and emerging mechanisms such as cardiac metabolic regulation and histone modification.Furthermore,the review emphasizes the modulation by NPs of novel targets or signaling pathways in classical mechanisms,including other forms of regulated cell death(RCD),endothelial-mesenchymal transition,non-coding ribonucleic acids(ncRNAs)cascade,and endothelial progenitor cell(EPC)function.Additionally,NPs influencing a particular mechanism are categorized based on their chemical structure,and their relevance is discussed.Finally,the current limitations and prospects of NPs therapy are considered,highlighting their potential for use in myocardial infarction management and identifying issues that require urgent attention.展开更多
Glioma,the most prevalent primary tumor of the central nervous system(CNS),is also the most lethal primary malignant tumor.Currently,there are limited chemotherapeutics available for glioma treatment,necessitating fur...Glioma,the most prevalent primary tumor of the central nervous system(CNS),is also the most lethal primary malignant tumor.Currently,there are limited chemotherapeutics available for glioma treatment,necessitating further research to identify and develop new chemotherapeutic agents.A significant approach to discovering anti-glioma drugs involves isolating antitumor active ingredients from natural products(NPs)and optimizing their structures.Additionally,targeted drug delivery systems(TDDSs)are employed to enhance drug solubility and stability and overcome the blood-brain barrier(BBB).TDDSs can penetrate deep into the brain,increase drug concentration and retention time in the CNS,and improve the targeting efficiency of NPs,thereby reducing adverse effects and enhancing anti-glioma efficacy.This paper reviews the research progress of anti-glioma activities of NPs,including alkaloids,polyphenols,flavonoids,terpenoids,saponins,quinones,and their synthetic derivatives over the past decade.The review also summarizes anti-glioma mechanisms,such as suppression of related protein expression,regulation of reactive oxygen species(ROS)levels,control of apoptosis signaling pathways,reduction of matrix metalloproteinases(MMPs)expression,blocking of vascular endothelial growth factor(VEGF),and reversal of immunosuppression.Furthermore,the functions and advantages of NP-based TDDSs in anti-glioma therapy are examined.The key information presented in this review will be valuable for the research and development of NP-based anti-glioma drugs and related TDDSs.展开更多
This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode ...This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode positive(DCEP)polarities yielded crack-free partial penetration welds for6 mm thick AZ31B alloy sheet.Welding under direct current electrode negative(DCEN)polarity with identical parameters as that for AC and DCEP resulted in full penetration welds that had microcracks.Defect-free full-penetration welds could be accomplished with pulse GTA welding using DCEN polarity at a pulse frequency of 1 Hz with a pulse duration ratio of 1:1.The resultant DCEN P 1:1 weld metal had a microstructure finer than the conventional DCEN weld.Welds produced with pulse duration ratios of 1:2and 1:4 lacked penetration but had a much finer microstructures because of the lower heat input.The arc constriction by the high frequency pulsing in the Activ Arc■-High frequency(AA-HF)mode welding was responsible for deeper penetration.Welds produced under DCEN pulsing and AA-HF conditions had hardness higher than conventional DCEN,DCEP and AC GTA welds,attributed to the finer microstructure.AA-HF GTA welding produced defect free deeper penetration welds with good microstructural features/mechanical properties and also gave an advantage of 50%enhanced productivity when welded at1500 Hz.展开更多
Seamless steel tubes,owing to their excellent integrity,structural properties,and processability,are widely applied in industries such as petroleum transportation,power and chemical industries,and national defense.How...Seamless steel tubes,owing to their excellent integrity,structural properties,and processability,are widely applied in industries such as petroleum transportation,power and chemical industries,and national defense.However,the stability of product quality in seamless steel tube production is often poor,particularly regarding the mechanical properties of intermediate products,which may not meet the required standards.This results in non-conforming products being unable to smoothly proceed to downstream processes.These issues mainly arise from the compactness of the production process,the characteristics of batch production,and the difficulty in managing order insertion.Consequently,optimizing the production process to minimize the impact of non-conforming products on subsequent processes has become a key challenge in seamless steel tube production.An intelligent reorganization production mechanism is proposed based on the full life cycle of seamless steel tubes,aiming at addressing the scheduling problems of tubes with abnormal performance.The mechanism utilizes a performance anomaly prediction model to detect and forecast potential anomalies in steel tubes,and in conjunction with intelligent scheduling strategies,rearranges the production plan for abnormal tubes.Experimental results demonstrate that the proposed mechanism can effectively improve the detection rate of abnormal tubes,significantly reduce time losses and energy consumption during production,and optimize both production cycles and stability.Specifically,the production cycle was shortened by 52 h,and energy consumption was reduced by approximately 12%.Through the intelligent scheduling model,the production plan was successfully optimized,reducing the production cycle and costs while improving production efficiency.The optimized scheduling scheme saved about 12%in production time,while enhancing the stability of the production plan and capacity utilization.展开更多
In-situ conversion of subsurface hydrocarbons via electromagnetic(EM)heating has emerged as a promising technology for producing carbon-zero and affordable hydrogen(H_(2))directly from natural gas reservoirs.However,t...In-situ conversion of subsurface hydrocarbons via electromagnetic(EM)heating has emerged as a promising technology for producing carbon-zero and affordable hydrogen(H_(2))directly from natural gas reservoirs.However,the reaction pathways and role of water as an additional hydrogen donor in EM-assisted methane-to-hydrogen(CH_(4)-to-H_(2))conversion are poorly understood.Herein,we employ a combination of lab-scale EM-heating experiments and reaction modeling analyses to unravel reaction pathways and elucidate water's role in enhancing hydrogen production.The labelled hydrogen isotope of deuterium oxide(D_(2)O)is used to trace the sources of hydrogen.The results show that water significantly boosts hydrogen yield via coke gasification at around 400℃and steam methane reforming(SMR)reaction at over 600℃in the presence of sandstone.Water-gas shift reaction exhibits a minor impact on this enhancement.Reaction mechanism analyses reveal that the involvement of water can initiate auto-catalytic loop reactions with methane,which not only generates extra hydrogen but also produces OH radicals that enhance the reactants'reactivity.This work provides crucial insights into the reaction mechanisms involved in water-carbon-methane interactions and underscores water's potential as a hydrogen donor for in-situ hydrogen production from natural gas reservoirs.It also addresses the challenges related to carbon deposition and in-situ catalyst regeneration during EM heating,thus derisking this technology and laying a foundation for future pilots.展开更多
In order to ensure food safety,controlling foodborne pathogen contamination is of utmost importance.Growing apprehensions regarding the safety of synthetic antimicrobials,due to their adverse health effects,have promp...In order to ensure food safety,controlling foodborne pathogen contamination is of utmost importance.Growing apprehensions regarding the safety of synthetic antimicrobials,due to their adverse health effects,have prompted a search for alternative options.Plant natural products(PNPs)with antimicrobial activity are being explored as a viable alternative.Among the various antimicrobial natural products studied,plant essential oils,plant flavonoids,plant polyphenols,plant polysaccharides,and plant antimicrobial peptides have been identified as potential candidates.PNPs demonstrate a diverse array of antimicrobial mechanisms,encompassing cell wall and membrane damage,interference with genetic replication,disruption of energy metabolism,and induction of oxidative stress at the single-cell level,as well as inhibition of biofilm formation and quorum sensing at the population level.Certain PNPs have been harnessed as natural antimicrobial agents for the food preservation.The utilization of encapsulation technology proves to be an effective strategy in protecting PNPs,thereby ensuring good antimicrobial efficacy,enhanced dispersibility,and controlled release within food products.The utilization of nanoemulsions,nanoliposomes,edible packaging,electrospun nanofibers,and microcapsules formed by encapsulation has enriched the ways in which PNPs can be applied in food preservation.Although PNPs have great potential in food preservation,their widespread application in the food industry is currently constrained by factors such as production costs,safety concerns,and legal considerations.Chemical synthesis and biosynthesis pathways offer viable strategies for reducing the cost of producing PNPs,and ongoing efforts to assess safety and improve regulatory frameworks are likely to facilitate the broader adoption of PNPs in food preservation practices.This article provides an overview of the main types of PNPs with antimicrobial activity and their properties,focusing on their mechanisms of action.Additionally,it summarizes the use of PNPs in food preservation and discusses the characteristics and applications of different encapsulation technologies.Lastly,the paper briefly analyzes current limitations and proposes potential future trends for this field.展开更多
Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation a...Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals.展开更多
When human immune function is compromised,infections caused by pathogenic fungi are often difficult to cure,with invasive fungal diseases frequently associated with high mortality rates.Presently,the types of antifung...When human immune function is compromised,infections caused by pathogenic fungi are often difficult to cure,with invasive fungal diseases frequently associated with high mortality rates.Presently,the types of antifungal drugs available for clinical use are limited,and their toxicity and safety issues can lead to adverse effects for patients.The emergence of drug-resistant strains and the“super fungus”Candida auris has further complicated treatment.Consequently,the identification of new antifungal medications and the formulation of effective combination therapy strategies have emerged as pivotal research priorities within this discipline.Natural products are specialized small molecules that are produced in nature and play pivotal roles in numerous cellular processes and are considered to be among the most significant pharmaceutical agents in the field of human healthcare.Accordingly,the objective of this paper is to review natural products and relevant compounds that exhibit antifungal activity by targeting key components of the fungal cell walls or cell membranes.We focused on the most recent research findings from 2022 to 2025 concerning antifungal natural products derived from plants,fungi,and bacteria,and conducted a comprehensive summary of the sources and types of natural products,along with their antifungal mechanisms of action.Furthermore,we analyzed the application prospects of combining novel natural products with existing antifungal drugs from the perspective of compensatory mechanisms of fungal cell structures,thus establishing new treatment strategies for fungal infections.展开更多
The development of new quality productivity has set new requirements for vocational education.Vocational colleges need to integrate ideological and political education into professional courses to cultivate high-quali...The development of new quality productivity has set new requirements for vocational education.Vocational colleges need to integrate ideological and political education into professional courses to cultivate high-quality talents with both technical capabilities and political literacy.This paper analyzes the connotation of new quality productivity and its reshaping of vocational education,explores the challenges faced by the educational mechanism of Curriculumbased Political and Ideological Education(CPIE),and proposes a“three-dimensional synergy”practical pathway.That is,to effectively promote CPIE through three dimensions:the deep integration of cases with professional content,the enhancement of teaching effects using digitization,and the optimization of the course evaluation system.It aims to provide theoretical support and practical references for the reform of ideological and political education in vocational colleges.展开更多
Cuban President Fidel Castro highly praised the products of Zhangjiakou’s Xuanhua Building Machinery Plant at a national conference in 1990. On the president’s recommendations, the Cuban ambassador to China conducte...Cuban President Fidel Castro highly praised the products of Zhangjiakou’s Xuanhua Building Machinery Plant at a national conference in 1990. On the president’s recommendations, the Cuban ambassador to China conducted an on-the-spot investigation and expressed his appreciation of the plant’s products. Besides Cuba, the plant’s products also enjoy a high reputation among customers in Pakistan, Chile, Australia, Papua New Guinea, Ghana and Southeast Asia. Zhangjiakou had its展开更多
Since the launch of the economic reform and opening to the outside world, China has seen rapid growth in its export of mechanical and electrical products, with its export
Mechanical and electrical products are more and more widely used in all the fields of the society. With the increase in the degree of automation and miniaturization, the structure of many mechanical and electrical pro...Mechanical and electrical products are more and more widely used in all the fields of the society. With the increase in the degree of automation and miniaturization, the structure of many mechanical and electrical products is becoming more and more complex, and the conditions of the use are also increasingly harsh, and therefore more and more product reliability issues are arising, and the reliability technology is being paid more and more attention to. In this paper, aiming at the mechanical and electtical products, from the three aspects of reliability management, reliability design and analysis, and reliability test and evaluation, the reliability research is preliminary studied.展开更多
Zhejiang’s machine-building industryhas made sustained efforts to increase itsexports through the combination ofindustry and trade. In the past decade,Zhejiang’s export volume of mechanicaland electrical products ha...Zhejiang’s machine-building industryhas made sustained efforts to increase itsexports through the combination ofindustry and trade. In the past decade,Zhejiang’s export volume of mechanicaland electrical products has increased over 10times, becoming the leading exports fromthe province. Zhejiang has thereforebecome an important province exportingmachinery in China.展开更多
The model for forecasting the test data on mechanical products is established in the application of the grey system theories. A new formula of the background value is introduced into the model. The result of an exampl...The model for forecasting the test data on mechanical products is established in the application of the grey system theories. A new formula of the background value is introduced into the model. The result of an example shows the method can reduce test expense and enhance the precision of forecasting.展开更多
The Measures for the Administration of the Import of Mechanical and Electronic' Products co-formulated by the Ministry of Commerce,the General Administration of Customs and the General Administration of Quality Su...The Measures for the Administration of the Import of Mechanical and Electronic' Products co-formulated by the Ministry of Commerce,the General Administration of Customs and the General Administration of Quality Supervision,Inspection and Quarantine,was hereby promul- gated,which entered into force as of May 1,2008.展开更多
基金supported by the National Natural Science Foundation of China(41902310,42372348,42372286)Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(2024ZD1003607)+2 种基金China Geological Survey Projects(DD20230700802,DD20221819)the Basic Research Fund of the Chinese Academy of Geological Sciences(JKYQN202306)Key Research and Development Program of Shanxi Province,China(202102090301009).
文摘The Mianhuakeng uranium deposit,characterized by uranium-rich granite,serves as a key site for research into crustal radioactive heating.Based on 45 rock samples,this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate(avg.5.50μW/m³)and a low Th/U ratio(avg.2.62).Uranium-rich granite and its alteration zone within the upper crust(0-5 km depth)contribute about 45%of the total radioactive heat production,wich is crucial for controlling geothermal resource distribution.For uranium-thermal at tectonic plate margins,a symbiotic geological model was proposed:Firstly,subduction of the Pacific Plate caused upwelling of the asthenosphere,generating a high heat-flow background.Secondly,heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults.Subsequently,uranium was mobilized,transported,and enriched within the granite through deep siliceous hydrothermal activity and associated alteration.Ultimately,the uranium enrichment in granite leads to increased radioactive heat production,resulting in local thermal anomalies.This model provides a theoretical support for exploring and developing uranium-thermal symbiotic resources in South China.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201303129)National Science and Technology Project for Bump Crop(2011BAD16B05)Scientific Research Foundation of Sichuan Agricultural University~~
文摘To clarify the effects of mechanical sowing and transplanting on dry mat- ter production of middle-season hybrid rice, a two-factor split plot design was used to study the effects of different sowing and transplanting methods and their interac- tion with the seedling number per hill or seeding time on dry matter accumulation, distribution and transformation of F You 498, a middle-season hybrid rice variety, under field conditions in 2012 and 2013. The results showed that there was a marked effect of the sowing and transplanting methods and their interaction with the seedling number per hill or seeding time on dry matter accumulation, distribution and transformation. The total population dry matter accumulation of the treatments with mechanical direct seeding （MDS） and machine-based transplanting （MT） was lower than that of the treatment with traditional manual transplanting （TMT）. How- ever, MDS had higher dry matter accumulation and accumulating rate in the joint- ing-earing stage,and maintained higher stem-sheath exportation, export rate and transformation than MT and TMT; MT had higher dry matter accumulation and ac- cumulating rate in the heading-maturity period than MDS and TMT. Moreover, the treatments with low seedling number per hill or early seeding enhanced the assimi- lation of dry matter after heading,the ratio of dry matter accumulation after earing to biomass yield and the contribution rate of dry matter accumulation after earing, and a reasonable early sowing was favorable to increase the harvest index of middle- season hybrid rice under mechanical sowing and transplanting conditions.
基金financially supported by the National Science Technology Supporting Program of China(No.2012BAE06B02)
文摘Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process of pressing, sintering, drawing, or rolling, respectively. By comparative analysis on the microstructure and mechanical properties of Mo wires and Mo sheets, the effect of Mo powder micro-morphology on properties and quality of Mo products was studied. The results show that, compared with that prepared by traditional Mo powder with inhomogeneous particle size and aggregation, the Mo wires prepared by specific Mo powder with homogeneous particle sizes, less agglomeration, and better dispersion exhibit higher yield, higher tensile strength, and lower elongation at room temperature, and the Mo sheets also show excellent high-temperature performances and better isotropy. The essential reason for those is the difference of Mo powder micro-morphology. Inhomogeneous particle size and aggregation of Mo powder greatly influence the microstructure of Mo sintered compacts and mechanical properties of Mo products.
基金This work is supported by the Science and Technology Planning Project of Ronggui(grant number RGJF(2017)27H-8).
文摘An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the elements.It divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve chains.The parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid elements.The average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve chains.Through the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between them.The method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning system.The examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering drawings.The dimension information is complete,accurate and reliable.
基金Supported by Daqing City Philosophy and Social Sciences Planning Research Project(DSGB 2025011)the Heilongjiang Province Education Science Planning Key Project(GJB1320229).
文摘Based on questionnaire surveys and field interviews conducted with various types of agricultural production organizations across five districts and four counties in Daqing City,this study combines relevant theoretical frameworks to systematically examine the evolution,performance,and influencing factors of governance mechanisms within these organizations.Using both quantitative and inductive analytical methods,the paper proposes innovative designs and supporting measures for improving governance mechanisms.The findings reveal that,amid large-scale farmland circulation,the governance mechanisms of agricultural production organizations in Daqing City are evolving from traditional to modern structures.However,challenges remain in areas such as decision-making efficiency,benefit distribution,and supervision mechanisms.In response,this study proposes innovative governance designs focusing on decision-making processes,profit-sharing mechanisms,and risk prevention.Corresponding policy recommendations are also provided to support the sustainable development of agricultural modernization in China.
基金supported by No. 82373870 from the National Natural Science Foundation of ChinaNo. 2022D01D50 from Xinjiang Natural Science Foundation
文摘Myocardial infarction is a cardiovascular disease(CVD)with high morbidity and mortality,which can trigger a cascade of cardiac pathophysiological changes,including fibrosis,inflammation,ischemia-reperfusion injury(IRI),and ventricular remodeling,ultimately leading to heart failure(HF).While conventional pharmacological treatments and clinical reperfusion therapy may enhance short-term prognoses and emergency survival rates,both approaches have limitations and adverse effects.Natural products(NPs)are extensively utilized as therapeutics globally,with some demonstrating potentially favorable therapeutic effects in preclinical and clinical pharmacological studies,positioning them as potential alternatives to modern drugs.This review comprehensively elucidates the pathophysiological mechanisms during myocardial infarction and summarizes the mechanisms by which NPs exert cardiac beneficial effects.These include classical mechanisms such as inhibition of inflammation and oxidative stress,alleviation of cardiomyocyte death,attenuation of cardiac fibrosis,improvement of angiogenesis,and emerging mechanisms such as cardiac metabolic regulation and histone modification.Furthermore,the review emphasizes the modulation by NPs of novel targets or signaling pathways in classical mechanisms,including other forms of regulated cell death(RCD),endothelial-mesenchymal transition,non-coding ribonucleic acids(ncRNAs)cascade,and endothelial progenitor cell(EPC)function.Additionally,NPs influencing a particular mechanism are categorized based on their chemical structure,and their relevance is discussed.Finally,the current limitations and prospects of NPs therapy are considered,highlighting their potential for use in myocardial infarction management and identifying issues that require urgent attention.
基金supported by the Project Program of Nature Science Foundation of Jiangsu Province of China(No.BK20201329)。
文摘Glioma,the most prevalent primary tumor of the central nervous system(CNS),is also the most lethal primary malignant tumor.Currently,there are limited chemotherapeutics available for glioma treatment,necessitating further research to identify and develop new chemotherapeutic agents.A significant approach to discovering anti-glioma drugs involves isolating antitumor active ingredients from natural products(NPs)and optimizing their structures.Additionally,targeted drug delivery systems(TDDSs)are employed to enhance drug solubility and stability and overcome the blood-brain barrier(BBB).TDDSs can penetrate deep into the brain,increase drug concentration and retention time in the CNS,and improve the targeting efficiency of NPs,thereby reducing adverse effects and enhancing anti-glioma efficacy.This paper reviews the research progress of anti-glioma activities of NPs,including alkaloids,polyphenols,flavonoids,terpenoids,saponins,quinones,and their synthetic derivatives over the past decade.The review also summarizes anti-glioma mechanisms,such as suppression of related protein expression,regulation of reactive oxygen species(ROS)levels,control of apoptosis signaling pathways,reduction of matrix metalloproteinases(MMPs)expression,blocking of vascular endothelial growth factor(VEGF),and reversal of immunosuppression.Furthermore,the functions and advantages of NP-based TDDSs in anti-glioma therapy are examined.The key information presented in this review will be valuable for the research and development of NP-based anti-glioma drugs and related TDDSs.
文摘This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode positive(DCEP)polarities yielded crack-free partial penetration welds for6 mm thick AZ31B alloy sheet.Welding under direct current electrode negative(DCEN)polarity with identical parameters as that for AC and DCEP resulted in full penetration welds that had microcracks.Defect-free full-penetration welds could be accomplished with pulse GTA welding using DCEN polarity at a pulse frequency of 1 Hz with a pulse duration ratio of 1:1.The resultant DCEN P 1:1 weld metal had a microstructure finer than the conventional DCEN weld.Welds produced with pulse duration ratios of 1:2and 1:4 lacked penetration but had a much finer microstructures because of the lower heat input.The arc constriction by the high frequency pulsing in the Activ Arc■-High frequency(AA-HF)mode welding was responsible for deeper penetration.Welds produced under DCEN pulsing and AA-HF conditions had hardness higher than conventional DCEN,DCEP and AC GTA welds,attributed to the finer microstructure.AA-HF GTA welding produced defect free deeper penetration welds with good microstructural features/mechanical properties and also gave an advantage of 50%enhanced productivity when welded at1500 Hz.
基金financially supported by Jiangxi Provincial Key R&D ProgrammeProjects(No.20223BBE51032)National Natural Science Foundation of China(No.52305336)the Opening Project of Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic Materials,South China University of Technology(No.GJ202411).
文摘Seamless steel tubes,owing to their excellent integrity,structural properties,and processability,are widely applied in industries such as petroleum transportation,power and chemical industries,and national defense.However,the stability of product quality in seamless steel tube production is often poor,particularly regarding the mechanical properties of intermediate products,which may not meet the required standards.This results in non-conforming products being unable to smoothly proceed to downstream processes.These issues mainly arise from the compactness of the production process,the characteristics of batch production,and the difficulty in managing order insertion.Consequently,optimizing the production process to minimize the impact of non-conforming products on subsequent processes has become a key challenge in seamless steel tube production.An intelligent reorganization production mechanism is proposed based on the full life cycle of seamless steel tubes,aiming at addressing the scheduling problems of tubes with abnormal performance.The mechanism utilizes a performance anomaly prediction model to detect and forecast potential anomalies in steel tubes,and in conjunction with intelligent scheduling strategies,rearranges the production plan for abnormal tubes.Experimental results demonstrate that the proposed mechanism can effectively improve the detection rate of abnormal tubes,significantly reduce time losses and energy consumption during production,and optimize both production cycles and stability.Specifically,the production cycle was shortened by 52 h,and energy consumption was reduced by approximately 12%.Through the intelligent scheduling model,the production plan was successfully optimized,reducing the production cycle and costs while improving production efficiency.The optimized scheduling scheme saved about 12%in production time,while enhancing the stability of the production plan and capacity utilization.
基金supported by a generous gift from The CH Foundationthe support from the Distinguished Graduate Student Assistantship and the Graduate Research Support Award at Texas Tech University+1 种基金the Aid fund from AAPGthe Matejek Family Faculty Fellowship。
文摘In-situ conversion of subsurface hydrocarbons via electromagnetic(EM)heating has emerged as a promising technology for producing carbon-zero and affordable hydrogen(H_(2))directly from natural gas reservoirs.However,the reaction pathways and role of water as an additional hydrogen donor in EM-assisted methane-to-hydrogen(CH_(4)-to-H_(2))conversion are poorly understood.Herein,we employ a combination of lab-scale EM-heating experiments and reaction modeling analyses to unravel reaction pathways and elucidate water's role in enhancing hydrogen production.The labelled hydrogen isotope of deuterium oxide(D_(2)O)is used to trace the sources of hydrogen.The results show that water significantly boosts hydrogen yield via coke gasification at around 400℃and steam methane reforming(SMR)reaction at over 600℃in the presence of sandstone.Water-gas shift reaction exhibits a minor impact on this enhancement.Reaction mechanism analyses reveal that the involvement of water can initiate auto-catalytic loop reactions with methane,which not only generates extra hydrogen but also produces OH radicals that enhance the reactants'reactivity.This work provides crucial insights into the reaction mechanisms involved in water-carbon-methane interactions and underscores water's potential as a hydrogen donor for in-situ hydrogen production from natural gas reservoirs.It also addresses the challenges related to carbon deposition and in-situ catalyst regeneration during EM heating,thus derisking this technology and laying a foundation for future pilots.
基金supported by the National Natural Science Foundation of China(32060520)Science and Technology Talents and Platform Program of Yunnan Province(202105AF150049)University Key Laboratory of Food Microbial Resources and Utilization in Yunnan Province(Yunjiaofa[2018]No.135).
文摘In order to ensure food safety,controlling foodborne pathogen contamination is of utmost importance.Growing apprehensions regarding the safety of synthetic antimicrobials,due to their adverse health effects,have prompted a search for alternative options.Plant natural products(PNPs)with antimicrobial activity are being explored as a viable alternative.Among the various antimicrobial natural products studied,plant essential oils,plant flavonoids,plant polyphenols,plant polysaccharides,and plant antimicrobial peptides have been identified as potential candidates.PNPs demonstrate a diverse array of antimicrobial mechanisms,encompassing cell wall and membrane damage,interference with genetic replication,disruption of energy metabolism,and induction of oxidative stress at the single-cell level,as well as inhibition of biofilm formation and quorum sensing at the population level.Certain PNPs have been harnessed as natural antimicrobial agents for the food preservation.The utilization of encapsulation technology proves to be an effective strategy in protecting PNPs,thereby ensuring good antimicrobial efficacy,enhanced dispersibility,and controlled release within food products.The utilization of nanoemulsions,nanoliposomes,edible packaging,electrospun nanofibers,and microcapsules formed by encapsulation has enriched the ways in which PNPs can be applied in food preservation.Although PNPs have great potential in food preservation,their widespread application in the food industry is currently constrained by factors such as production costs,safety concerns,and legal considerations.Chemical synthesis and biosynthesis pathways offer viable strategies for reducing the cost of producing PNPs,and ongoing efforts to assess safety and improve regulatory frameworks are likely to facilitate the broader adoption of PNPs in food preservation practices.This article provides an overview of the main types of PNPs with antimicrobial activity and their properties,focusing on their mechanisms of action.Additionally,it summarizes the use of PNPs in food preservation and discusses the characteristics and applications of different encapsulation technologies.Lastly,the paper briefly analyzes current limitations and proposes potential future trends for this field.
基金supported by the National Key Research and Development Program of China(No.2020YFA0607800)the National Natural Science Foundation of China(Nos.42022039 and 42130606)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202011),the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y2021013).
文摘Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals.
基金supported by the National Natural Science Foundation of China(No.82322075).
文摘When human immune function is compromised,infections caused by pathogenic fungi are often difficult to cure,with invasive fungal diseases frequently associated with high mortality rates.Presently,the types of antifungal drugs available for clinical use are limited,and their toxicity and safety issues can lead to adverse effects for patients.The emergence of drug-resistant strains and the“super fungus”Candida auris has further complicated treatment.Consequently,the identification of new antifungal medications and the formulation of effective combination therapy strategies have emerged as pivotal research priorities within this discipline.Natural products are specialized small molecules that are produced in nature and play pivotal roles in numerous cellular processes and are considered to be among the most significant pharmaceutical agents in the field of human healthcare.Accordingly,the objective of this paper is to review natural products and relevant compounds that exhibit antifungal activity by targeting key components of the fungal cell walls or cell membranes.We focused on the most recent research findings from 2022 to 2025 concerning antifungal natural products derived from plants,fungi,and bacteria,and conducted a comprehensive summary of the sources and types of natural products,along with their antifungal mechanisms of action.Furthermore,we analyzed the application prospects of combining novel natural products with existing antifungal drugs from the perspective of compensatory mechanisms of fungal cell structures,thus establishing new treatment strategies for fungal infections.
基金supported by the Beijing Municipal Commission of Education(Project Leader:Shang Wang,Project No.ZYJYDJ2024049).
文摘The development of new quality productivity has set new requirements for vocational education.Vocational colleges need to integrate ideological and political education into professional courses to cultivate high-quality talents with both technical capabilities and political literacy.This paper analyzes the connotation of new quality productivity and its reshaping of vocational education,explores the challenges faced by the educational mechanism of Curriculumbased Political and Ideological Education(CPIE),and proposes a“three-dimensional synergy”practical pathway.That is,to effectively promote CPIE through three dimensions:the deep integration of cases with professional content,the enhancement of teaching effects using digitization,and the optimization of the course evaluation system.It aims to provide theoretical support and practical references for the reform of ideological and political education in vocational colleges.
文摘Cuban President Fidel Castro highly praised the products of Zhangjiakou’s Xuanhua Building Machinery Plant at a national conference in 1990. On the president’s recommendations, the Cuban ambassador to China conducted an on-the-spot investigation and expressed his appreciation of the plant’s products. Besides Cuba, the plant’s products also enjoy a high reputation among customers in Pakistan, Chile, Australia, Papua New Guinea, Ghana and Southeast Asia. Zhangjiakou had its
文摘Since the launch of the economic reform and opening to the outside world, China has seen rapid growth in its export of mechanical and electrical products, with its export
文摘Mechanical and electrical products are more and more widely used in all the fields of the society. With the increase in the degree of automation and miniaturization, the structure of many mechanical and electrical products is becoming more and more complex, and the conditions of the use are also increasingly harsh, and therefore more and more product reliability issues are arising, and the reliability technology is being paid more and more attention to. In this paper, aiming at the mechanical and electtical products, from the three aspects of reliability management, reliability design and analysis, and reliability test and evaluation, the reliability research is preliminary studied.
文摘Zhejiang’s machine-building industryhas made sustained efforts to increase itsexports through the combination ofindustry and trade. In the past decade,Zhejiang’s export volume of mechanicaland electrical products has increased over 10times, becoming the leading exports fromthe province. Zhejiang has thereforebecome an important province exportingmachinery in China.
文摘The model for forecasting the test data on mechanical products is established in the application of the grey system theories. A new formula of the background value is introduced into the model. The result of an example shows the method can reduce test expense and enhance the precision of forecasting.
文摘The Measures for the Administration of the Import of Mechanical and Electronic' Products co-formulated by the Ministry of Commerce,the General Administration of Customs and the General Administration of Quality Supervision,Inspection and Quarantine,was hereby promul- gated,which entered into force as of May 1,2008.
